Question

How many gallons of a plant food that is 6% nitrogen must be combined with another plant food that is 30% nitrogen to make 10 gal of a plant food that is 15% nitrogen?

Answer 1

x = 6 1/4

y = 3 3/4

Explanation:

let 'x' = gallons of 6% nitrogen

let 'y' = gallons of 30% nitrogen

system of equations:

x + y = 10; let y = 10-x

6x + 30y = 10(15)

substitute '10-x':

6x + 30(10-x) = 150

6x + 300 - 30x = 150

-24x = -150

x = 6 1/4

y = 3 3/4